As is generally known, a diaphragm spring is a component for urging a pressure plate toward a friction facing of a clutch disc. A pull-type clutch is so designed that an inner peripheral part of the diaphragm spring is connected to a release bearing and is moved backward in an axial direction of the clutch when the release bearing is moved in an axial direction away from a flywheel (backward in the axial direction). The clutch is thus disengaged.
An example of a conventional pull-type clutch is shown in FIG. 5. In such clutch, a clutch disc 12 is fixed to a clutch output shaft 11 and, a friction facing 13 provided at an outer periphery of the clutch disc 12 is urged toward a flywheel 15 by a pressure plate 14, to engage the clutch. An annular diaphragm spring 9 is positioned at an axial backside of the pressure plate 14, and urges the pressure plate 14 toward the facing 13. A radial peripheral portion of the diaphragm spring 9 contacts the pressure plate 14 and is supported by a fulcrum point 17 of a clutch cover 16 secured to the flywheel 15. The diaphragm spring 9 has radial slits 10 extending from radial intermediate portions to inner peripheral parts 9a, and the inner peripheral parts 9a are connected to a release bearing 1. The release bearing 1 fits onto an outer periphery of the clutch output shaft 11 through a sleeve 20. A lever 18 connected to a clutch pedal (not shown), moves release bearing 1 backward in the axial direction when the clutch pedal is depressed.
A mechanism connecting release bearing 1 and the inner peripheral part 9a of the diaphragm spring 9, in the conventional pull-type clutch, is shown in FIG. 6 in an enlarged manner. A wedge collar 2 fits onto an outer periphery of the release bearing 1 (inner race portion). The wedge collar 2 has a radial outward flange 2a at its radial axial backside end. A substantially V-shaped bent portion 2b formed at an axial forward tip end, fits onto a substantially V-shaped groove 1a formed at an axial forward tip end of the release bearing 1. An outer peripheral surface of the bent portion 2b has an annular groove 2c. A snap ring 3 is attached to the groove 2c. An axial forward tip end 2d of the wedge collar 2 extends forward in the axial direction and opens into a tapered shape relative to the snap ring 3. The snap ring 3 is thereby prevented from slipping off, in the axial forward direction, from the wedge collar 2.
Lever plate 4 is installed on an outer periphery of the wedge collar 2 with the snap ring 3 therebetween. The lever plate 4 integrally has a radial outward flange 5 at an axial forward end of a cylindrical body. FIG. 7 is a view showing the entire lever plate 4 viewing in a direction VII of FIG. 6, and, FIG. 8 is a sectional view taken on a line VIII--VIII of FIG. 7. The flange 5 includes, at its intermediate portion an extension 50 which has an arcuate section extending backward in the axial direction of flange 5. In lever plate 4, FIG. 6 an annular stepped part 4a which engages with the snap ring 3 from the axial backside, is formed on a surface facing on an outer periphery of the wedge collar 2, and a tapered guide surface 4b is formed on an inner peripheral end adjacent to the tip end 2d of wedge collar 2. Because the wedge collar 2 is fit onto the outer periphery of the release bearing 1 and the lever plate 4 is fit onto the outer periphery of the wedge collar 2, so as to engage with the snap ring 3 at the stepped part 4a, as described above, the wedge collar 2 is moved together with and in the same direction as the lever plate 4 when the release bearing 1 is moved backward in the axial direction.
The flange 5 is coupled, by a retainer plate 6, to the diaphragm spring 9 immovably in axial forward and backward directions. The retainer plate 6 integrally contains axially forward bent projections 8, at plural places, on a radial outer periphery of a disc-like annular body 7. FIG. 9 is a view of the entire retainer plate 6, viewing in a direction IX of FIG. 6, and FIG. 10 is a sectional view taken on a line X--X of FIG. 9. The bent projections 8 extend through the plural slits 10 of the diaphragm spring 9 and through grooves 5c, provided at a radial outer periphery of the flange 5, and tip ends 8a bent inwardly, in radial directions, engage with a radial outside portion of an axial front side surface 5a of the flange 5. The body 7 includes, at its intermediate portion, an extension 70 having an arcuate section and extending forward in the axial direction.
The inner peripheral part 9a of the diaphragm spring 9 is sandwiched between the body 7 of the retainer plate 6 and the flange 5 of the lever plate 4, as illustrated by FIG. 6 and FIG. 11. In FIG. 11, bent projections 80 (FIG. 9 & FIG. 10) which are formed alternately with the bent projections 8 in a circumferential direction of the retainer plate 6, pass only through the slits 10 of the diaphragm spring 9 but are not engaged with the lever plate 4.
In the pull-type clutch as constructed above, however, the bent projections 8 of the retainer plate 6 are made engage with the lever plate 4 through the slits 10 of the diaphragm spring 9, so that it is hard for the lever plate 4 to move relative to the diaphragm spring 9. For this reason, when a deviation between centers of the lever plate 4 and the flywheel 15 at time of manufacture was produced, a misalignment arises because of difficulty in remedy of the deviation. Such a misalignment will cause an assembly state of deviated centers between the clutch and transmission, so that vibration of the clutch pedal and breakage of the sleeve 20 (FIG. 5) will result. If widths of the slits 10 of the diaphragm spring 9 are widened, to allow the lever plate 4 to move relative to the diaphragm spring 9, the bent projections 8 of the retainer plate 6 will be worn out quickly. In order to solve this problem, a countermeasure may be taken in which a part of the bent projection 8 is subjected to carbon-proof and sintering processes. However, this measure is troublesome and requires a high cost.
It is an object of this invention to provide a pull-type clutch which allows the relative movement between the lever plate and the diaphragm spring so as to absorb the misalignment easily, and for preventing the clutch pedal from vibrating and the sleeve from being damaged.